This nonprovisional application claims priority under 35 U.S.C. xc2xa7119(a) on Patent Application No. 2001-029495 filed in Japan on Feb. 6, 2001, the entirety of which is herein incorporated by reference.
1. Field of the Invention
The present invention relates to a movable body progress direction navigating apparatus for navigating a movable body such as a vehicle or a walking human being, for example, in a predetermined progress direction. In particular, the present invention is directed to a movable body progress direction navigating apparatus which is portable to facilitate the carriage, for example, on two-wheeled vehicles and pedestrians, to correctly navigate them from a via-point in a predetermined direction.
2. Description of Related Art
Navigation systems for displaying an optimum route from a start point to a destination through registration beforehand are in wide use. In addition, a navigation system (a first related art technology) having a back-track mode and known as product name xe2x80x9cMagellan GPS 3000 Satellite Navigatorxe2x80x9d has been sold since December 1995 in Japan from Mazellan Systems Japan Corporation. In the first related art technology, via-points are sequentially registered as xe2x80x9cwaypointsxe2x80x9d halfway between a start point and destination. Furthermore, in a return mode, the registered waypoints are followed in a reverse manner to correctly reach the start point by traveling along the same route as the outward route. In this back-track mode, the distance and direction from each waypoint to another are displayed in each return route.
In a technology (a second related art technology) disclosed in Japanese Patent Laid-open No. Hei 11-14390, when registering via-points beforehand, the longitude and latitude of each via-point are inputted as via-point data. At the same time, the progress direction from each via-point is inputted as an absolute bearing, thereby displaying a progress direction of a movable body when it approaches each via-point.
In the above-mentioned first related art technology, the current positions can be registered as via-point data (waypoints) during traveling; however, the approach direction to each waypoint and the departing direction therefrom cannot be registered. Consequently, as shown in FIG. 9, the progress direction represented by waypoint WP2 in the back track mode in the return route becomes the direction of the next (one point before in approach route) waypoint WP1 as shown in a dashed-line circle.
Hence, as shown, unless the direction of the line segment connecting between adjacent waypoints WP2 and WP1 matches the direction of the road running from waypoint PW2 to waypoint PW1, a wrong return route displayed at waypoint WP2 may be indicated.
Although the above-mentioned problem can be solved by registering many waypoints during traveling, it increases a memory capacity necessary for storing the registered waypoints. Accordingly, such a solution is unrealistic.
In the above-mentioned second related art technology, the progress direction from each via-point inputted for the approach route cannot be used for the return route. Therefore, similar to the above-mentioned first related art technology, if the road status is as shown in FIG. 9, the movable body may be navigated along a wrong return route.
It is therefore an object of the present invention to solve the above-described problems, and to provide a movable body progress direction navigating apparatus, which correctly navigates a movable body without requiring a large memory capacity.
In order to attain the above object, the present invention is directed to a movable body progress direction navigating apparatus for navigating a movable body in a predetermined direction, including a position detector for continuously detecting positional data of a movable body to obtain a position thereof; a directional data generator for generating, on the basis of the locus of the movable body, at least one of approach directional data obtained when the movable body has entered into a predetermined via-point and departing directional data obtained when the movable body has departed from the via-point; a directional data storage for storing at least one of the approach direction data and the departing directional data in association with positional data of the via-point; and when the movable body has approached the via-point, a navigator for navigating the movable body in a predetermined progress direction, on the basis of at least one of the approach directional data or the departing directional data, whichever is stored in the directional data storage.
According to the above-mentioned characteristics, the approach directional data and departing direction data of a movable body are stored in memory for each via-point. Accordingly, when the movable body subsequently passes each via-point again, the movable body can be correctly navigated in the normal direction from each via-point on the basis of the stored approach directional data and departing directional data.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.